Project Goals:† Comparing
the refractive index and the absorption of doped quantum dots to indium doped
and tin dope quantum dots.† Also to
compare these results to what was obtained when there was a comparison between
charged and uncharged quantum dots.

Project Statement: †My project was on the terahertz
spectroscopy of undoped, tin doped and indium doped CdSe Quantum dots.† I purified the quantum dots, added some
polystyrene and dissolved all in toluene and then evaporated the toluene
leaving a small circular solid cast behind and then did the terahertz
measurement of that.† The polystyrene is
transparent in terahertz. The terahertz time domain spectroscopic technique
directly measures the terahertz wave temporal electric field that allows
precise measurements of the refractive index and the absorption coefficients.
This way Iíll be able to compare the refractive indexes of doped and undoped
quantum dots.† Quantum dots are a special
class of semiconductors, which are a cornerstone of modern electronics industry
and make possible applications such as the light emitting diode and personal
computers.† They are very small ranging
from 2 to 10 nanometers in diameter and at these very small sizes materials
have unprecedented tunability enabling never before seen applications in
science and technology. Doping or the use of intentional impurities (in this
case tin and indium) to control the behavior of materials lies in the heart of
many technologies.† Doping is critical
for semiconductors that can be otherwise electrically insulating or to increase
the conductivity of semiconductors hence changing its electrical and optical
properties.† Doped and undoped quantum
dots have many unique applications in industries such as in the making of
medical devices, bio-reagents and electronics.†
Comparing different doping materials and undoped materials is useful so
as to tell which materials are suitable for the particular applications they
are needed for.

Week 1:†
Read through a number of papers such as Plasmon-Phonon Coupling in
Charged n-Type CdSe Quantum dots; A THz Time Domain Spectroscopic study so
that by understanding what people have done before with Quantum dots and since
some of the hiongs are similar to what I would be doing I would get a feel for
my project.

Week 2; Read through more papers that
described lasers† since I had never
worked with lasers before, and more papers on doping, phonons and the
generation and Detection of the infrared Radiation.† Started on working on trying to make
polystyrene cylinders that did not contain quantum dots just for practicesí
sake. They did not come out well.

Week 3:†
Read more on lasers.† Worked some
more successfully on producing smooth cylinders that were of the required
thickness.† Also that is when I first
worked with a laser.† We cleaned it up,
realigned it and worked on optimizing its power output.

Week 4: I made the cylinders with some
undoped CdSe dots.† Also we mode locked
the laser and took some terahertz measurement of the cylinders I had
produced.† Also I made some cylinders
with some† CdSe dots that are doped with
tin (Sn).

Week 5: †I made some cylinders with some Indium dope in
them after purifying the quantum dots.†
Put an indium doped sample to take the terahertz measurement of the
sample.

Week 6: Took the samples with tin, undoped
samples with some quantum dots and one without and took some measurements of
it.† Also read on several articles on
terahertz spectrometry.

Week 7: Purified more quantum† dots and made one more cylinder with indium
dope.† Gave Kristan Corwin a tour in the
lab.† Read more in detail about what
quantum dots are and how the terahertz signal is produced.† Gave a presentation in the group meeting.

Week 8:†
Made more undoped samples.† Took
terahertz measurements of some samples

Week 9: Took more terahertz measurements of
my samples.† Read on a previous study
that had been done with charged and uncharged quantum dots

Week 10:†
Worked on my powerpoint presentation, final paper and did the final
presentation!

This had been a great summer.† Would like to thank Larry Weaver, Kristan
Corwin, Prof Viktor Chikan, all those I worked with in the lab for being such
wonderful people and helping us get some experience in the physics world